Ledian is a moderately large, bipedal creature with a rather large head and six small limbs. It also has star patterns on its back, which grow larger or smaller depending on the number of stars visible in the night sky. Each spot represents a corner of a star shape. These spots have also been observed glowing red during twilight hours as Ledian are attached to trees, making these trees seem like Christmas trees. Male Ledian are shown having longer antennae than females.
Ledian is a nocturnal insect, active mainly during the night and sleeping in curled-up leaves during the day. Countless Ledian live in outdoor areas located a good distance away from the polluted atmospheres of cities, for the star-lit skies are always clearer in these clean lands than in the light pollution of urban areas. Ledian have an affinity to stars for good reason; They take their energy from the light of the stars in order to live healthily. When many stars are visible, the Ledian will sprinkle a mysterious, glowing powder whilst fluttering about.
Ledian was first introduced in Season 4 in the episode Mountain Time, where Ash and co. met Benji with a young Ledian. Benji was learning from his father what being a mountain ranger was like, while Benji's Ledian was learning how to fly in strong winds from Benji's father's Ledian, possible it's parent. Benji and his Ledian aided in the rescue of Pikachu and Togepi when they were Pokénapped by Team Rocket. In the end, both Benji's and his father's Ledian's spots on their backs began to glow a bright red as they circled high in the evening starlight sky showering everyone with beautiful starlight.
Ledian had a few minor appearances afterwards and a slightly bigger role in Mewtwo Returns. Ledian was seen in some of the Grand Festival episodes and was one of the Pokémon used to try to stop Darkrai in The Rise of Darkrai.
It is possible that Ledian is a portmanteau of the words "ladybug" and "alien", given its appearance.
Even though Ledian is a Flying type Pokémon, it can't learn any Flying type moves via level-up.